NCERT Class-9 Science Solutions: Chapter 3-Atoms and Molecules Part 3

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Question 10:

A change in the physical state can be brought about

  1. Only when energy is given to the system

  2. Only when energy is taken out from the system

  3. When energy is either given to, or taken out from the system

  4. Without any energy change

Answer: C

Short Answer Questions

Question 11:

Which of the following represents a correct chemical formula? Name it.

Answer: B

Question 12:

Write the molecular formulae for the following compounds

  1. Copper (II) Bromide

  2. Aluminium (III) Nitrate

  3. Calcium (II) Phosphate

  4. Iron (III) Sulphide

  5. Mercury (II) Chloride

  6. Magnesium (II) Acetate


Question 13:

Write the molecular formulae of all the compounds that can be formed by the combination of following ions


Image of molecular Formula

Image of Molecular Formula

Image of molecular Formula

Question 14:

Write the cations and anions present (if any) in the following compounds


Anions and Cations
Result for Anions and Cations

Sr. No






It is a covalent compound